Download Refining aquacultural practices

DRS IAN FLEMING AND CRAIG PURCHASE
Refining aquacultural practices
As the aquaculture industry continues to grow worldwide, Drs
Ian Fleming and Craig Purchase are concerned with making the
practice as efficient and sustainable as possible. Here, they talk
about their studies so far and insights that can be drawn
To begin, could you discuss the inspiration
for this project and outline your goals?
What interests you in the behavioural and
evolutionary ecology of fish?
IF: This is a general research issue that I have
worked on since 1991 in Norway, when we
were among the first to quantify concerns
related to escapes from salmon aquaculture.
With the recent expansion of marine fish
aquaculture into new species, it was clear that
similar issues existed; but the challenges were
new and different. Our goals are to ultimately
provide insight that may aid in environmentally
sustainable practices for aquaculture.
I am fascinated by trying to understand and
predict how and why animals, particularly
fishes, respond to their environment in the
way they do – through plasticity, genetics and
transgenerational effects. This approach gives
incredible insight into the effects of changing
environments, climate and human impacts on
biological systems, and potential approaches
to sustainability.
Could you elucidate the genetic tools and
techniques you use in this research?
IF: We use molecular genetics principally
to track growth, survival and associated
fitness measures in individual family groups,
and to assess parentage in natural breeding
experiments. We are also beginning to
explore genomic techniques to identify
factors affecting gene expression during
critical life history events.
How would interbreeding affect both wild
and farmed cod? What impact would it
have on supply?
CP: There are two issues relating to
interbreeding between farmed and wild cod
that can have negative consequences for
the latter:
Firstly, species which have wide
geographical distributions often have
populations that adapt to their local
environments. Aquaculture operations
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usually raise specific strains of a given
species because of attributes desirable for
domestication, such as relatively fast growth
rates and large size at maturity. When the
cultured fish of a non-native population
escape, they can interbreed with wild
individuals and genetically dilute the specific
adaptations of the local populations, which
may reduce its productivity.
Secondly, under agriculture, or aquaculture, the
raising of organisms usually involves a period
of domestication through artificial selection,
such that specific individuals are bred each
generation to develop a brood stock that has
attributes desirable for farming situations.
This evolution can breed out aggressive
behaviour, slow growth, early maturation,
and so on. Through multiple generations
the resulting animals under culture are very
different from the wild species from which they
originated, meaning farmed animals can have
poor survival in the wild. Thus, if they escape
and interbreed with wild animals, they can
genetically pollute those populations, which
can greatly reduce productivity. This is rarely a
concern with traditional agriculture, as there
are rarely wild animals in the area of farms to
breed with. However, aquaculture operations
often take place in the natural habitat of the
species being farmed.
Do you conduct both field and laboratory
experiments in this assay? Why is each
one necessary?
IF: Both field and laboratory experiments are
instrumental to the research we undertake.
The laboratory experiments allow us to control
variables and investigate specific effects,
which cannot be done in the field, while field
experiments allow us to scale up to natural
systems and test hypotheses that are affected
by the vagaries of nature.
What has been your most significant
finding thus far?
IF: It is difficult to identify one finding as being
the most significant – rather the many findings
contribute to an overall picture. Our results
indicate that marine fish such as cod will spawn
readily within sea cages, even closely related
individuals, and the resulting offspring may
disperse widely from the cage in what is known
as ‘egg escape’. Moreover, marine fish such
as cod behave differently than salmon in sea
cages, interacting much more with the netting.
Although we have identified possible means
of mitigating the behaviour through nutrition
and cage enrichment, once the fish escape
our findings indicate that they will disperse
rapidly and widely, overlapping with wild
populations and following similar migratory
routes, indicative of a potential for negative
interactions. Our results may be applied to the
emerging cod aquaculture industry, as well as
that of other marine fish, to reduce the number
of escapes, streamlining the development of
the industry before mitigation becomes too
difficult and costly to implement.
DR JOHN BRATTEY
RELEASING A COD TAGGED
WITH AN ACOUSTIC
TRANSMITTER
Evaluating the impact of
aquacultural escapees
INTELLIGENCE
ASSESSING AND MITIGATING RISK
FROM A DIVERSIFYING AQUACULTURE
INDUSTRY: THE POTENTIAL FOR
INTERACTION BETWEEN ESCAPEE AND
WILD ATLANTIC COD
OBJECTIVES
Concerns have existed for two decades about the impact of escaped farmed
fish on wild populations. A new study in Newfoundland, Canada, is seeking
to understand this better, and to improve practice and policy accordingly
AQUACULTURE IS A rapidly growing industry.
In the face of worldwide decreases in wild stocks
of many fish, aquaculture is emerging as an
economically important method for meeting
the global demand for, amongst others, salmon
and cod. In rural coastal areas of Canada,
aquaculture has become a big employer, with
fish constituting a significant export for the
Canadian economy. Given this, it is no wonder
that Canadian aquaculture projects are seeking
novel ways to make their operations both more
efficient and more sustainable.
A NEW STUDY
A new study by Drs Ian A Fleming and Craig F
Purchase, both of the Memorial University of
Newfoundland, Canada, is aimed at assessing
and mitigating the risks from a diversifying
aquaculture industry, with particular focus on
the potential for interaction between escapees
from aquaculture and wild fish. Whilst as much
as possible is done to avoid escapes through
technological improvements to cages, better
situated farms and progress in fish handling and
rearing, some remain inevitable, especially given
the sheer quantity of fish in captivity.
Escapes by captive fish are problematic for a
number of reasons. Not only do they cost the
farmers economically, but they are likely to breed
with wild fish. Fleming explains: “Interbreeding
between wild and farmed cod can disrupt local
adaptation, particularly when farmed cod
derive from non-local sources or have been
domesticated. As a consequence, the survival
of hybrid offspring is almost certainly reduced
and the productivity of the wild population
likely diminished”. Even in the absence of
such interbreeding, there can be detrimental
ecological effects on wild populations in terms of
competition, predation and the spread of disease.
A FIVE POINT PLAN
Fleming and Purchase have focused their new
study on five key knowledge gaps. Firstly, they
are seeking to determine the likelihood that cod
will reproduce with siblings within aquaculture
cages, and the resultant quality of the inbred
embryos that might be released into the wild.
Secondly, they are looking to find new ways
to reduce the motivation of cod to escape
from farms. Thirdly, a tagging scheme is being
piloted in order that fish which have escaped
can be monitored, in an attempt to determine
how easily they could be recaptured and their
likelihood to interact with wild fish populations.
Fourthly, controlled mating experiments are
being carried out to establish the probability
of interbreeding between escaped farmed and
native wild cod, which will enable the study to
evaluate the potential for traits from aquaculture
fishes to be introduced into the wild. Finally, the
team is also working on laboratory experiments
which will seek to explore whether there is
indeed a lower growth and survival rate amongst
hybridised populations in the wild.
There is clearly a hugely practical application to
all this work, and Fleming and Purchase remain
optimistic that their findings will result in a more
effective Canadian response to the challenges
which are being posed by the swift growth in
aquaculture. “Canada currently has no federal
legislation specifically addressing aquaculture; the
Canadian aquaculture policy framework derives
largely from various other policy documents,”
Fleming notes. “It is evident that there is a need
for reform through the development of an
‘Aquaculture Act’.”
To determine the nature of the interactions
between farmed and wild cod and from this,
provide a means to assess risk and identify
mitigation measures. The results aim to reduce
potential ecological effects, as well as industry
costs of escapes from aquaculture and improve
Canada’s ability to respond to the science and
policy challenges presented by the growth of its
aquaculture industry.
KEY COLLABORATORS/PARTNERS
Dr Edward Trippel, Saint Andrews Biological
Station – Fisheries and Oceans Canada • Dr John
Brattey, Northwest Atlantic Fisheries Centre
– Fisheries and Oceans Canada • SINTEFF/
EU Prevent Escape Consortium (http://
preventescape.eu) • Fish Food and Allied
Workers • Cod Genome Project • Ocean
Tracking Network
FUNDING
Natural Sciences and Engineering Research
Council of Canada
CONTACT
Dr Ian A Fleming
Professor, Department of Ocean Sciences
Ocean Sciences Centre
Memorial University of Newfoundland
St John’s, Newfoundland & Labrador, A1C 5S7
Canada
T +1 709 864 3586
E [email protected]
PRACTICAL APPLICATIONS
www.mun.ca/osc/ifleming/
As part of the project, Fleming and Purchase have
worked with a number of industry stakeholders,
including aquaculture and fisheries interests and
both governmental and non-governmental bodies,
in order to work towards a better aquaculture
practice. Additionally, they have sought the
collaboration and expertise of some of Europe’s
leading biologists and engineers, in particular Dr
Tim Dempster of SINTEF (The Foundation for
Scientific and Industrial Research at the Norwegian
Institute of Technology) in Norway, who heads up
the EU Prevent Escape programme.
Dr Craig F Purchase
Assistant Professor, Department of Biology
Science Building
Memorial University of Newfoundland
St John’s, Newfoundland & Labrador, A1B 3X9
Canada
Despite its recent growth, aquaculture still has its
critics, and Purchase recognises why this might be
the case. “A large part of aquaculture, particularly in
the developed world, is not to produce fish protein,
but to produce a certain type of fish protein that
people in the developed world prefer to eat,” he
underlines. “Salmon, for instance, eat fish, so if more
lower trophic level fish protein is used to produce 1
kg of salmon, there is a potential net loss of food
for human consumption.” However, Fleming and
Purchase are confident that their studies will not
only bear fruit, but will have a concrete and lasting
impact on aquaculture practices, making the
burgeoning form of production as responsible and
sustainable as possible.
T +1 709 864 4452
E [email protected]
www.ucs.mun.ca/~cfpurchase
IAN FLEMING is a Professor in the Department
of Ocean Sciences of Memorial University and
its former Director (2004-9). His research
integrates perspectives from ecology and
evolution with fishery and conservation biology. CRAIG PURCHASE has been an Assistant
Professor of Biology at Memorial University
since 2008. His research primarily focuses on
how fishes have adapted to their environments,
and has direct implications for productivity and
conservation of populations.
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